why int is the default data integer type in java code example

Example: all data types in java

Data Type	Size	Stores
byte		1 byte	whole numbers from -128 to 127
short		2 bytes	whole numbers from -32,768 to 32,767
int			4 bytes	whole numbers from -2,147,483,648 to 2,147,483,647
long		8 bytes	whole numbers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
float		4 bytes	fractional numbers; sufficient for storing 6 to 7 decimal digits
double		8 bytes	fractional numbers; sufficient for storing 15 decimal digits
boolean		1 bit	true or false values
char		2 bytes	single character/letter or ASCII values